boiled egg republic of korea superheated lee sang kyu

Boiled Egg

Republic of KoreaSuperheatedLee Sang kyu

Contents

1. Experimental setup1. Torsion viscometer

2. Theoretical Explanation1. Force induced by viscosity2. Energy loss in one period3. Inertia of moment4. Solidification of egg

3. Experiment4. Analysis5. Result6. Conclusion

1. Problem

Construct a torsion viscometer. Use it to investigate the differences in the 'viscous' properties of hens' egg that have been boiled to different extents.

2. Basic Idea

Torsion viscometer– Device to measure viscosity using the fact

that viscosity of liquid intervenes rotation of torsion pendulum.

– Using this principle, it is possible to know the egg’s viscous properties without breaking it.

Viscosity

dv

dy : Shear stress

: Velocityv

: viscosity

: depthy

3. Experimental Setup

Egg

Aluminum cyllinder

(Making I even greater)

Rotation Sensor

Spring (Making the periodic oscillation)

4. Theoretical Explanation

Liquid in the egg will make the oscillation damping.

Supposing an egg as an ellipsoid :2 2

2 21

x y

a b

: angular velocity

x

y

a

b

2

21x

y ba

4cylinderA xy

viscosity ( ) 4dv

F x A xydy

2

0

4

3

aFdx a b

Theoretical Explanation cont.

k b

2

2

4

34

3

rF b b a b

b a b

Equation of damping oscillation of torsion device is :

Resisting force in the damping oscillation is :

Energy loss in one period(Energy damping)

Energy damping– From the device

Device has toothed wheels, making the loss of energy proportional to its rotating amount = angular position change

– From the egg Expected to be proportional to (angular velocity)2,

as is any damping oscillation.

2dEb

dt

Inertia moment

1. Egg (assuming that it’s shaped like an ellipsoid)

r

x

y 2 2ax y c 2y c ax

2dm r dx41

2dI r dx

22 4 2 2

2

1 8( 2 )

2 15

0.0000327

c

ac

a

c acI a x acx c dx

a

kg m

2. Device (cylinder)20.000651I kg m

Solidification of egg

Supposed boiling process of egg

Heat

Boiling time (sec. In 100℃

water)

Thickness of solidified albumen

30 1.9mm

60 2.4mm

90 3.35mm

120 4.4mm

180 Complete

Viscosity : Same

Viscous property : Change (As amount of liquid changes)

Experiment

Device

General damping oscillation

Damping Oscillation

Time (sec.)

Angle (deg)

All the damping oscillation

Damping Oscillation with eggs boiled to various degrees

Unboiled egg

Boiled egg to various degrees

Analysis

Energy loss from the device is proportional to the angular position change, as the toothed wheel in the sensor is the main friction source.

Angular position change during one period (deg)

0.2398E

Energy loss from

the device (J)

Analysis cont.

Leaving out energy loss from the device, the one from egg remains to be proportional to (angular velocity)2 (Everything in 15℃)

1. It is not proportional

2. Slightly boiled egg had less viscous effect than expected

(angular velocity)2 mean value in one period (deg/s)2

Energy dam

ping from

the egg in one period (J)

Why not proportional?

0 sec. Boiled egg’s graph is :

A

B

C A region : Too slow : Less energy loss from the device

B region : Almost same as expected

C region : Too fast : Albumen can’t follow the solid part : less viscous property than expected.

Why less viscous than expected?

Unboiled egg 30 sec. Boiled egg

Why less viscous than expected? Cont.

Actual boiling process

Heat

“Viscous effect” of an egg when boiled to different extent

Result

Boiled time(s

)

b Viscosity, (relative viscous

property)

0 4.88e-5 1.457 Pa·s (1)

30 2.58e-5 (0.529)

90 1.90e-5 (0.389)

120 1.22e-5 (0.250)

150 7.32e-6 (0.150)

180 7.27e-6 (0.149)

Liquid Viscosity

(Pa·s)

Glycerin 1.17

Lubricating oil

0.1~1

Water 0.00114

Conclusion

A torsion viscometer can be made using damping effect of viscous liquid.

Measured viscosity– 1.457 Pa·s

Egg is to solidify when boiled, making its viscous effect less.– Egg liquid is so sticky that some expectations

are wrong about the egg– And as its solidification fixes yolk at particular

position, make the egg much less viscous.

Energy loss fitting in B part

Fitting proportionally

Analysis cont.

Too slow 와 Too fast!!

General damping oscillation

Damping Oscillation

Time

Angle (deg)

All the damping oscillation

Damping Oscillation with eggs boiled to various degrees

How to fit

Fitting the graphs as following :